3.3. What is the origin of the name Godzilla?

Godzilla vs. Mothra

The original Japanese name of Godzilla is Gojira. According to
the Sanseido Concise Gairaigo Jiten (dictionary of foreign loan words)
the original English spelling was "Gozilla". No one seems to know how
the "d" got there. The change from ji to zi results from a
difference of romanization systems (see 1.3.4. What are the systems of romanization of Japanese?). The usual
explanation of the origin of Gojira is that this word is a
combination of two words gorira (gorilla) and kujira
(whale). However the following information from the Godzilla FAQ may
shed some more light:

Did you know how Gojira (Godzilla in Japanese) was named? According
to Eiji Tsuburaya, the creator of Godzilla: "At the time, there was a
tough- looking guy working on the Toho lot. His nickname was
`Gojira'. We just adopted it for our monster. It caught on and
certainly has immortalized him!"

External links

The Godzilla FAQ referred to can be found
here. This site
does not belong to the original author of the FAQ.